Biomedical subjects

L Yee

Publications and source records attributed to L Yee.

28 records · Page 2Linked to original sources

PubMed1993

Clinical predictors of post-traumatic seizures in children with head trauma.

STUDY OBJECTIVES: To determine the clinical characteristics associated with early post-traumatic seizures in children with head trauma. DESIGN, SETTING, AND TYPE OF PARTICIPANTS: Retrospective chart review; urban trauma center/pediatric emergency department. Trauma patients aged 3 months to 15 years given discharge diagnosis ICD-9-CM codes indicating head trauma and seen from 1988 to 1990 were eligible for the study. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 194 patients, 96% suffered blunt trauma and 53% had a loss of consciousness. Fifty-one percent of 141 computed tomography (CT) scans of the head were abnormal, most frequently demonstrating skull fractures (34%), subdural hematomas (15%), and cerebral contusions (14%). Eighteen patients (9.3%) suffered post-traumatic seizures. A loss of consciousness, a low Glasgow Coma Scale (GCS) score (3 to 8), and an abnormal CT scan were associated with post-traumatic seizures (P < .02, .001, and .02, respectively). However, only a low GCS score was predictive of post-traumatic seizures when these factors were considered simultaneously (P < .001), with 38.7% of patients with low GCS scores suffering post-traumatic seizures and 3.8% of patients with high GCS scores suffering post-traumatic seizures. In children with low GCS scores, treatment with phenytoin was associated with a decrease in post-traumatic seizures. CONCLUSION: In the pediatric head trauma patient, a GCS score of 3 to 8 appears to be predictive of post-traumatic seizures. The data from this retrospective study are consistent with the hypothesis that prophylactic phenytoin reduces post-traumatic seizures in the pediatric head trauma patient with a low GCS score.

Adolescent↗

PubMed1992

Recombinant protein expression in high cell density fed-batch cultures of Escherichia coli.

Whereas cell concentrations of 5-10 grams dry cell weight per liter (gDCW/l) are typical of batch cultures, fed-batch techniques can be used to achieve concentrations greater than 50 gDCW/l. Feeding strategies for fed-batch cultures include feed-back control as well as pre-determined feeding profiles. The volumetric yield of recombinant products can be improved by controlling the specific growth rate and the substrate concentration. Furthermore, inhibitory by-product formation can be minimized in fed-batch cultures. This review focuses on the use of fed-batch techniques to produce recombinant products in Escherichia coli. The modes of nutrient feeding that have been employed are discussed, and the factors important in attaining high cell concentrations as well as high specific yields of recombinant product are described.

Bacteriological Techniques↗

PubMed1990

Age- and gender-related influence on the lacrimal gland and tears.

Previous research has demonstrated that distinct, gender-related differences exist in lacrimal glands in a variety of adult species. The objective of the current investigation was to examine whether this influence of gender extends throughout development and aging. Towards that end, morphological parameters of the lacrimal gland, as well as the volume, protein and IgG content of tears, were measured in male and female infant, preweanling, pubertal, adult, mid-life and senescent rats. Our results showed that dramatic, age-related variations occurred in the weight and morphological appearance of the lacrimal gland. Moreover, the magnitude of structural changes was dependent upon gender. Acinar area was significantly greater in lacrimal tissue of males, as compared to females, at all ages except pre-weanling; this sexual dimorphism was most evident in senescent rats. In contrast, acinar density in lacrimal glands of females was higher than, or equal to, that of males throughout development and aging. With regard to tears, pronounced increases were evident in tear volume, protein and IgG content from the pre-weanling stage to adulthood. After this time, these tear indices tended either to plateau or rise slightly until senescence. Gender had little or no impact of the volume of, or protein and IgG level in, tears. Of interest, the IgG/protein ratio in tears was 49- to 105-fold less than that found in lacrimal tissue, indicating that IgG moves down a gradient from the lacrimal gland to tears. Overall, our findings demonstrate that gender has a significant influence on lacrimal gland structure during development and aging. However, this impact is limited with respect to tear volume and protein content.

Aging↗

PubMed1990

Influence of ocular surface antigen on the postnatal accumulation of immunoglobulin-containing cells in the rat lacrimal gland.

The objective of the present study was to determine whether antigenic presence on the ocular surface might directly influence the development or expression of the lacrimal secretory immune system. Experiments were designed to: (i) analyse the temporal accumulation of IgA-, IgG- and IgM-containing cells in lacrimal tissue during postnatal development (6-27 days of age); (ii) examine whether prevention of antigenic exposure to the ocular surface by unilateral tarsorrhaphy might inhibit lymphocyte immigration into the ipsilateral gland during development; and (iii) assess whether a non-invasive antigen, after placement on the ocular surface of infant or adult rats, undergoes retrograde transfer to the lacrimal gland. Our results demonstrated that: (i) the accumulation of IgA-, IgG- and IgM-containing cells in lacrimal tissue was most pronounced during the 6-day period after eyelid opening (15 days of age). The pattern of appearance of these Ig-containing cells, which were predominantly IgA-positive, was identical in both left and right lacrimal glands. (ii) Closure of the left lid by tarsorrhaphy from 10 to 18 days of age had no effect on the accumulation of IgA-, IgG- and IgM-containing cells in the left lacrimal tissue compared to cell numbers in the right gland. (iii) Following placement of radiolabelled albumin on the ocular surface, antigen was almost completely cleared within 1-2 hr. Analysis of lacrimal glands showed no significant accumulation of radioactivity at any time-point, either in the presence or absence of ocular inflammation. In contrast, up to 17.8% of radioactivity was found in the stomach 1-2 hr following topical antigen application. Overall, our results show that a rapid development of the lacrimal secretory immune system occurs between 15 and 21 days of age. This process does not appear to be dependent upon local antigenic stimulation. In addition, our findings indicate that a non-invasive antigen, when applied to the ocular surface, does not undergo retrograde transfer to the lacrimal gland. Instead, antigen appears to be cleared primarily through the gastrointestinal tract.

Aging↗

PubMed1989

Mutagenesis of the Tra1 core region of RK2 by using Tn5: identification of plasmid-specific transfer genes.

The conjugation system of the IncP alpha plasmid RK2/RP4 is encoded by transfer regions designated Tra1, Tra2, and Tra3. The Tra1 core region, cloned on plasmid pDG4 delta 22, consists of the origin of transfer (oriT) and 2.6 kilobases of flanking DNA providing IncP alpha plasmid-specific functions that allow pDG4 delta 22 to be mobilized by the heterologous IncP beta plasmid R751. Tn5 insertions in pDG4 delta 22 define a minimal 2.2-kilobase region required for plasmid-specific transfer of oriT. The Tra1 core contains the traJ and traK genes as well as an 18-kilodalton open reading frame downstream of traJ. The traJ and traK genes were shown to be required for transfer by complementation of inserts within these genes. Genetic evidence for the role of the 18-kilodalton open reading frame in transfer was obtained, although this protein has not been detected in cell lysates. These studies indicate that at least three transfer proteins are involved in plasmid-specific interactions at oriT.

Bacterial Proteins↗

PubMed1983

Adhesion-blocking antibodies prepared against gp150 react with gp80 of Dictyostelium.

A membrane glycoprotein of 150 000 D, gp150, has been implicated in the mechanism of cell-cell adhesion which arises during development of Dictyostelium discoideum. This conclusion was founded on the observation that monovalent Fab' fragments prepared from an antiserum raised against partially purified gp150 are able to block cell-cell adhesion. We show that this serum contains antibodies to a distinct membrane glycoprotein, gp80, previously implicated in cell-cell adhesion. Reaction of Fab' to this surface molecule can account for the adhesion-blocking activity in the antiserum to gp 150. Moreover, binding of gp80 neutralized Fab' to gp150 does not block adhesion. If gp150 carries other determinants which bind adhesion-blocking Fab', these determinants must also be present on gp80. Thus, it is not clear that gp150 is directly involved in cell-cell adhesion of Dictyostelium.

Antibodies↗

PubMed1981

Comparison of nearpoint techniques.

Thirteen subjects, 11 males and 2 females, from 24 to 35 years of age, were tested at the nearpoint. Three testing procedures, the Mallett near unit, the traditional examination technique, and the Borish nearpoint card, were performed. Results were analyzed to see whether a significant difference exists between the 3 types of nearpoint testing techniques. The Borish card differed significantly from the traditional technique (p less than .05) on tests of visual acuity, unfused crossed cylinder and fused cross cylinder. Donder's amplitude of accommodation on the Mallett unit and on the Borish card differed significantly (p less than .05). No significant difference was noted with the traditional technique versus the Borish card on tests of lateral phoria, vertical phoria, and vergences, or between the Mellett and Borish test on lateral associated phorias, vertical associated phorias, fine suppression, balance of sphere at near and cylinder power at near. Gross suppression was found in 2 of 26 measurements on the Mallett tests. No subjects indicated gross suppression on the Borish card.

Adult↗

PubMed1976

Olfactory recognition of conspecifics by domestic Norway rats.

In order to learn more about their ability to recognize one another via olfaction, domestic male rats were given a series of preference tests in which pairs of odors from male conspecifics were presented. Both immature and mature males prefer (p less than .05) the odor from immature strangers over that from immature cage mates but are indifferent to the ordors from mature strangers versus cage mates. Both immature and mature males prefer (p less than .05) the odor from mature novel cage mates over that from mature cage mates to which they are temporarily habituated but are indifferent to the odors from immature novel versus familial cage mates. Mature males prefer (p less than .08) the odor from a cage mate over the subject's own odor, and they prefer (p less than .01) their own odor over no odor. Under certain conditions, male rats can discriminate between the odors from (a) strangers versus cage mates, (b) two cage mates, and (c) their own body versus a cage mate.

Age Factors↗

PubMedDate not supplied

Evaluation of residual instability after arthroscopic meniscectomy in anterior cruciate deficient knees.

Forty-five patients who underwent a partial meniscectomy in an anterior cruciate deficient knee were followed from 2 to 9 years. The average age at the time of the meniscectomy was 28.6 years. The majority of the patients were injured in recreational athletics. The subjects were evaluated preoperatively by a questionnaire and clinical examination, both of which were repeated at followup. The efficacy of the postsurgical rehabilitation was monitored with measurement of quadriceps and hamstring strength on the Cybex Dynamometer. All of the patients had a KT-1000 knee ligament arthrometer test at followup that was compared with the clinical examination. Sixty-five percent of the subjects (13 of 20) with a Lachman and pivot shift of +1 returned to their previous activity level without limitation. Of the patients with a KT-1000 compliance index of 1 mm, 70% (11 of 17) returned to the same athletic level. However, only 20% (2 of 11) of the patients with a clinical instability greater than +1 or a compliance index of 2 mm were able to perform without limitation. The location of the meniscal tear did not correlate with the functional outcome. Six patients required ACL reconstruction.

Adult↗

PubMedDate not supplied

Neural-immune interrelationship: effect of optic, sympathetic, temporofacial, or sensory denervation on the secretory immune system of the lacrimal gland.

Previous research has demonstrated that the nervous system may exert a significant impact on lymphocyte distribution and function in certain mucosal tissues. Given this neural-immune interaction, the present study was designed to evaluate whether ocular nerves might influence the distribution, density, and output of IgA-containing cells in the lacrimal gland. Male Sprague-Dawley rats were subjected to one of the following surgical protocols: denervation of the temporofacial, optic, or trigeminal nerves or ablation of the superior cervical ganglion. Denervations were performed on one side and sham-operations on the contralateral side. Additional groups of rats were exposed to bilateral sham or complete optic nerve disruption. Two to four weeks after surgery, tears were collected from individual eyes for the measurement of IgA and protein levels and lacrimal glands were processed for the immunofluorescent identification of IgA-containing cells. Our results showed that a marked heterogeneity is present in the frequency distribution of IgA-containing cells in lacrimal tissue sections of sham-operated rats. Statistical analysis of this distribution showed that the topographical location of IgA-containing cells per section or through the gland was not random. This heterogeneity did not appear to be modified by interrupting various nerves to the eye. Moreover, severance of the temporofacial, optic, or trigeminal nerve supplies or extirpation of the superior cervical ganglion did not significantly alter either the density or total number of IgA-containing cells in the lacrimal gland, as compared to values in contralateral "sham-operated" tissues. In addition, these neural disruptions had no apparent influence on the IgA content or the IgA/protein ratio in tears.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗